Jixxers, landscape fabric is used for keeping the weeds etc from growing up thru it. It also helps to keep the soil in place under the fabric/rocks from wave erosion. In my case the lake is some 750' wide and I get white cap waves lapping up on the east shoreline where my riprap is located. If your water is narrow this wouldn't be a problem. The amount of rock depends on how far into the water and out of the water you want the rip rap rock to cover but it will be 15-20 tonnes plus with 2-3 layers of rock over each other. I hope this helps.

Rowly